Date: Mon, 14 Jul 2014 15:34:02 +0900
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Rik van Riel <riel@redhat.com>, Peter Zijlstra <peterz@infradead.org>,
        Mel Gorman <mgorman@suse.de>, Johannes Weiner <hannes@cmpxchg.org>,
        Minchan Kim <minchan@kernel.org>,
        Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
        Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
        "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
        Tang Chen <tangchen@cn.fujitsu.com>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Wen Congyang <wency@cn.fujitsu.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Michal Nazarewicz <mina86@mina86.com>,
        Laura Abbott <lauraa@codeaurora.org>,
        Heesub Shin <heesub.shin@samsung.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        Ritesh Harjani <ritesh.list@gmail.com>, t.stanislaws@samsung.com,
        Gioh Kim <gioh.kim@lge.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 08/10] mm/page_alloc: use get_onbuddy_migratetype() to
 get buddy list type
Message-ID: <20140714063401.GD11317@js1304-P5Q-DELUXE>
References: <1404460675-24456-1-git-send-email-iamjoonsoo.kim@lge.com>
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 <53BAC37D.3060703@suse.cz>
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On Mon, Jul 07, 2014 at 05:57:49PM +0200, Vlastimil Babka wrote:
> On 07/04/2014 09:57 AM, Joonsoo Kim wrote:
> >When isolating free page, what we want to know is which list
> >the page is linked. If it is linked in isolate migratetype buddy list,
> >we can skip watermark check and freepage counting. And if it is linked
> >in CMA migratetype buddy list, we need to fixup freepage counting. For
> >this purpose, get_onbuddy_migratetype() is more fit and cheap than
> >get_pageblock_migratetype(). So use it.
> 
> Hm but you made get_onbuddy_migratetype() work only with
> CONFIG_MEMORY_ISOLATION. And __isolate_free_page is (despite the
> name) not at all limited to CONFIG_MEMORY_ISOLATION.

get_onbuddy_migratetype() is only used for determining whether this
page is on isolate buddy list or not. So if !CONFIG_MEMORY_ISOLATION,
default value of get_onbuddy_migratetype() makes things correct.

But, I should write some code comment.

Thanks.
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